This removes the need for the EventsLoop::interrupt method by inroducing
a ControlFlow type. This new type is to be returned by the user's
callback and indicates whether the `EventsLoop` should continue waiting
for events or break from the loop.
Only the wayland, x11 and api_transition backends have been updated so
far, and only the wayland backend has actually been tested.
X11 and Wayland implementations are now half implemented, however both
still do not correctly break from the inner blocking event dispatch
functions when `wakeup` is called, which they should do.
If the interrupted flag were set going into poll_events, it would only
ever handle the first event in the queue. Now, the flag is reset at the
start so events are processed until the caller requests otherwise.
This is the same behavior as with WindowProxy::wakeup_event_loop in
previous versions.
Unfortunately, `EventsLoop::interrupt` is also the recommend way to exit
a `run_forever` loop from within the event handler callback. Pushing an
extra event on the queue in that case is simply wasteful. Changing this
would require a refactor taking one of two possible forms:
1. Add a method *in addition* to interrupt intended for waking up the
event loop
2. Add a return type to the event callback like
enum Continue { True, False }
which would be used in lieu of the atomic interrupt flag.
It was only processing a single event per call. The docs say
> Fetches all the events that are pending, calls the callback function
> for each of them, and returns.
which suggests that was incorrect.
All platforms should now receive events in the following order:
1. KeyboardInput(ElementState::Pressed, ..)
2. ReceivedCharacter
3. KeyboardInput(ElementState::Released, ..)
cc https://github.com/tomaka/glutin/issues/878
This expands input events to represent sub-pixel mouse positions, devices responsible for generating events, and raw
device-oriented events. The X11 back end is refactored to make full use of the new expressiveness. Other backends have
had new functionality minimally stubbed out, save for the macos backend which already supports sub-pixel mouse
positions.
